Some standard content:
GB/T15038-94
National Standard of the People's Republic of China
General test methods for wine and fruit wine
Analytical methods of wineand fruit wine1 Subject content and scope of application
This standard specifies the basic principles and test methods for quality inspection of wine and fruit wine products. This standard applies to the quality inspection of wine and fruit wine products. 2 Referenced standards
Preparation of standard solutions for titration analysis (volumetric analysis) of chemical reagents Preparation of standard solutions for determination of impurities of chemical reagents Preparation of preparations and products used in chemical reagent test methods GB6031
GB1250
GB6682
GB8170
Expression and determination methods of limit values Specifications and test methods for laboratory water
Rules for rounding off values
GB/T102 20
General Introduction to Sensory Analysis Methods
GB/T13868 Sensory Analysis General Guidelines for Establishing Sensory Analysis Laboratories GB/T14195 Selection and Training of Sensory Analysis Guidelines for Selecting Sensory Analysis Evaluators 3 General Principles and Basic Requirements
3.1 General Principles
GB/T15038—1994
3.1.1 The various analytical instruments used in this method must be calibrated on time; the glassware used should be calibrated according to the relevant verification procedures.
3.1.2 The "instruments" in this method are special instruments that must be used in the test, and general laboratory instruments are no longer included. 3.1.3 The water used in this method, unless otherwise specified, shall meet the specifications of Grade 3 water in GB6682. 3.1.4 The reagents used in this method, unless otherwise specified, are all analytically pure (AR). 3.1.5 "Solution" in this method refers to aqueous solution unless otherwise specified. "Dilution to scale" means diluting to the specified volume with water.
3.1.6 The density of a substance in this method refers to the mass of a substance per unit volume at 20°C, expressed in g/L; the concentration of a standard solution is expressed as the molar concentration c, expressed in mol/L; the volume percentage is expressed as % (V/V); the number of grams of a solute contained in a certain volume is expressed in g/L; a specific solution of volume Vi is added to a solvent of volume V2, expressed as "Vi+V,"
3.1.7 "Sample" in this method refers to a laboratory sample, which refers to a wine sample sent to a laboratory or extracted for laboratory inspection or testing; a "test sample" is a sample prepared from a laboratory sample; and a "test portion" is a certain amount of sample or test sample measured (weighed) for inspection. 3.1.8 When there are two or more test methods for the same test item, each laboratory can choose according to its own conditions, but the first method shall be the arbitration method.
3.1.9 The effective mathematics in the test method indicates the precision required when aspirating or weighing. For example: aspirate 5.00mL of sample; weigh 2g of sample, accurate to 0.00019. 3.1.10 Report the test results as measured data; the effective figures of the results must be consistent with the technical requirements. The calculation and selection of test results and test data shall be carried out in accordance with GB8170. The limit numerical expression and judgment method of the results shall be carried out in accordance with Article 5.2 "Rounded value comparison method" in GB1250. 3.1.11 The general guidelines for sensory analysis shall be implemented in accordance with GB/T10220. Approved by the State Administration of Technical Supervision on May 5, 1994 1
Implementation on December 1, 1994
GB/T15038-94
3.2 Basic requirements
3.2.1 Parallel tests must be conducted for the determination of samples. 3.2.2 The glassware used in the test must be cleaned with chromic acid detergent or synthetic detergent before use, then rinsed with tap water, and then rinsed with distilled water. When determining metal ions, it must first be soaked in 10% nitric acid solution for at least 24 hours, and then rinsed with tap water and deionized water (in accordance with the GB6682 secondary water specification) in sequence. 4 Sensory analysis method
4.1 Principle
Sensory analysis refers to the inspection and analysis and evaluation of the sensory characteristics of wine and fruit wine products by the evaluator through the sense organs such as mouth, eyes and nose, that is, the color, aroma, taste and typicality of the sensory characteristics of wine and fruit wine products. 4.2 Wine Tasting Conditions
4.2.1 Laboratory Requirements
According to GB/T13868.
4.2.2 Evaluators
According to GB/T14195.
4.2.3 Tasting Cup
See Figure 1 for the tasting cup.
4.2.4 Temperature Adjustment
Adjust the temperature of the wine after removing the label to: 9~10℃ for sparkling and aerated sparkling wine; 10~11℃ for white wine (ordinary); 12~14℃ for rosé wine; 13~15℃ for white wine (high quality); 16~18℃ for red wine (dry, semi-dry, semi-sweet) and fruit wine (semi-dry, semi-sweet); 18~20℃ for aromatized wine, sweet red wine and sweet fruit wine.
4.2.5 Sequence and numbering
When there are multiple types of samples in a tasting inspection, the tasting order is: white first, then red, first white, then sweet, first light, then strong, first new, then old, first low, then high. Number the samples in order and indicate the same number at the bottom of the wine glass. 4.2.6 Pouring wine
Wipe the outside of the tempered wine bottle clean and open the cork (cap) carefully without letting any foreign matter fall in. Pour the wine into a clean, dry tasting glass. Generally, the height of the wine in the glass should be 1/4 to 1/3, and the height of sparkling and aerated sparkling wines should be 1/2.
4.3 Sensory inspection and evaluation
4.3.1 Appearance
Approved by the State Administration of Technical Supervision on May 5, 19942
Implemented on December 1, 1994
GB/T15038-94
Under appropriate light (not direct sunlight), hold the bottom of the glass or the stem of the glass with your hand, raise the glass to your eyebrows, and observe the color, transparency and clarity of the wine in the glass, and whether there are sediments and suspended matter; for sparkling and aerated sparkling wines, observe the bubbles and make detailed records.
4.3.2 Aroma
First, use the nose mask to smell several times in a static state, then hold the wine glass in your palm to warm the wine slightly, and shake the glass to distribute the wine sample on the wall of the glass. Slowly place the wine glass under your nostrils, smell its volatile aroma, distinguish the fruity aroma, wine aroma or other strange aromas, and write a comment. 4.3.3 Taste
Drink a small amount of sample in your mouth, try to distribute it evenly in the taste area, taste it carefully, swallow it after you have a clear impression, and then experience the taste and aftertaste, and record the taste characteristics. 4.3.4: Typicality
Based on the comprehensive analysis of the characteristics of appearance, aroma, and taste, evaluate its type, style, and typicality, and write a conclusion (or score).
5 Physical and chemical test methods
5.1 Alcohol content
The first method is gas chromatography
5.1.1 Principle
When the sample passes through the chromatographic column in the gas chromatograph, ethanol is separated from other components due to the different adsorption coefficients in the gas and solid phases. It is identified using a hydrogen flame ionization detector and quantified using the internal standard method. 5.1.2 Reagents and solutions
5.1.2.1 Ethanol: chromatographically pure (GR), used as standard sample. 5.1.2.2 n-Propanol: density = 803.9 g/L, chromatographically pure (GR), used as internal standard. 5.1.2.3 Ethanol standard solution (A): use 5 100 mL volumetric flasks to absorb 2.00, 3.00, 3.50, 4.00, 4.50 mL of ethanol (5.1.2.1), and then add water to 100 mL. 5.1.2.4 Ethanol standard solution (B): use 5 10 mL volumetric flasks to accurately measure 10.00 mL of ethanol solution standard (A) (5.1.2.3) of different concentrations, and then add 0.50 mL of n-propanol internal standard solution to each, and mix well. This solution is used to draw the standard curve.
5.1.3 Instruments and equipment
5.1.3.1 Gas chromatograph: equipped with red flame ionization detector. Chromatographic column (stainless steel or glass): 2m×2mm or 3m×3mm5.1.3.21
Stationary phase: Chromosorb103, 60-80 mesh, or other column materials with similar performance. 5.1.3.3
5.1.3.4 Micro syringe.
5.1.4 Preparation of sample
Accurately dilute the sample 4 times (or dilute appropriately according to the alcohol content), then draw 10.00mL into a 10mL volumetric flask, accurately add 0.50mL of n-propanol internal standard solution, and mix well. 5.1.5 Analysis steps
5.1.5.1 Selection of chromatographic conditions
a. Reference conditions:
Column temperature: 200℃;
Vaporization chamber and detector temperature: 240℃;
Carrier gas flow rate (nitrogen): 40mL/min; Hydrogen flow rate: 40mL/min;
Air flow rate: 500mL/min.
Approved by the State Administration of Technical Supervision on May 5, 19943
Implemented on December 1, 1994
GB/T15038-94
b. Selection conditions:
Referring to the above conditions, the best operating conditions are selected through experiments according to the conditions of different instruments, that is, ethanol and n-propanol are completely separated, and ethanol is eluted in about 1 minute (see Figure 2 for a typical chromatogram). 1.13
5.1.5.2 Drawing of standard curve: Take 0.3uL of ethanol standard solution B (5.1.2.4) respectively, and quickly inject it into the chromatograph from the injection port. At the same time, turn on the recorder to record the spectrum. Use the ratio of the peak area of the standard sample to the peak area of the internal standard to make a standard curve for the alcohol concentration (or establish a corresponding regression equation). 5.1.5.3 Determination of sample: Take 0.3uL of sample (5.1.4) and operate according to 5.1.5.2. 5.1.6 Calculation
The value obtained by checking the standard curve using the ratio of the peak area of the sample component to the peak area of the internal standard (or the value calculated using the regression equation) and multiplying it by the dilution factor is the alcohol content in the wine sample. The result should be expressed to one decimal place. 5.1.7 Permissible difference of results
The absolute value difference of the results of parallel tests shall not exceed 0.05% (V/V). Method 2 Density bottle method
5.1.8 Principle
Use distillation to remove non-volatile substances in the sample, and use the density bottle method to determine the density of the distillate. According to the density of the distillate (alcohol-water solution), check Appendix A (Supplementary) to obtain the volume percentage of ethanol at 20℃ (%, V/V), that is, the alcohol content.
5.1.9 Instruments
5.1.9.1 Analytical balance: sensitivity 0.0001g. 5.1.9.2 All-glass distiller: 500mL. 5.1.9.3 High-precision constant temperature water bath: 20.0±0.1℃. 5.1.9.4 Density bottle with thermometer: 25 or 50mL (see Figure 3). Blood breaking
5.1.10 Preparation of sample
The test is carried out under the working conditions of 20℃±5℃. Use a clean, dry 100mL volumetric flask to accurately measure 100.0mL of sample (liquid temperature 20℃) into a 500mL distillation flask. Rinse the volumetric flask with 50mL of water three times, add the washing liquid into the distillation flask, add a few glass beads, connect the condenser, and use the original volumetric flask used for sampling as a receiver (with an ice bath). Turn on the cooling water and slowly heat and distill. Collect the distillate close to the scale of the State Administration of Technical Supervision on May 5, 1994, 4
1994-12-01 implementation
GB/T15038-94
, remove the volumetric flask and cover it. Keep warm in a 20℃ water bath for 30 minutes, add water to the scale, mix well, and set aside. 5.1.11 Analysis steps
5.1.11.1 Determination of distilled water quality
a. Wash and dry the density bottle, and weigh it with a thermometer and side hole cover. Repeat drying and weighing until constant weight (m). b. Remove the thermometer, fill the constant-weight density bottle with distilled water that has been boiled and cooled to about 15°C, insert the thermometer, and there should be no bubbles in the bottle. Immerse the density bottle in a constant-temperature water bath at 20.0±0.1°C. When the temperature of the contents reaches 20°C and remains unchanged for 10 minutes, use filter paper to absorb the liquid overflowing from the side tube so that the liquid level in the side tube is flush with the side tube mouth, immediately cover the side hole cover, take out the density bottle, wipe the water on the bottle wall with filter paper, and immediately weigh (m). 5.1.11.2 Measurement of sample mass
Pour out the water in the density bottle, wash it and dry it, then fill it with the sample prepared in 5.1.10, and do the same as 5.1.11.1b. and weigh (m2).
5.1.12 The density of the sample distillate at 20℃ is calculated according to formula (1) and (2): mz-m+A
m,-m+A
Wherein: P20
density of the sample distillate at 20℃, g/L; m
-mass of the density bottle, g:
m—total mass of the density bottle and the distilled water filling the density bottle at 20℃, g: m2—— Total mass of density bottle and sample distillate filling density bottle at 20℃, g; Po—density of distilled water at 20℃ (=998.20g/L); A
air buoyancy correction value;
density of dry air at 20℃, 1013.25hPa (~1.2g/L1)): 997.0-
—difference between density of distilled water and dry air at 20℃, g/L. Note: 1) This value varies slightly with air pressure conditions, but this change generally has no effect on density determination. According to the density β2020 of the sample distillate, check Appendix A (Supplement) to obtain the alcohol content. The result is expressed to one decimal place.
5.1.13 Permissible difference of results
The absolute value difference of the results of parallel tests shall not exceed 0.1% (V/V). Method 3 Alcoholometer method
5.1.14 Principle
Use distillation to remove non-volatile substances in the sample, and use the alcoholometer method to measure the alcohol volume percentage indication. According to Appendix B (Supplement), perform temperature correction to obtain the volume percentage of ethanol at 20°C (%, V/V), i.e., the alcohol content. 5.1.15 Instrument
5.1.15.1 Alcoholometer (division value is 0.1 degree). 5.1.15.2 All-glass distiller: 1000mL. 5.1.16 Preparation of sample
Use a clean, dry 500mL volumetric flask to accurately measure 500mL1) sample (liquid temperature 20°C) into a 1000mL distilling flask. The following operations are the same as 5.1.10. Approved by the State Administration of Technical Supervision on May 5, 19945
Implemented on December 1, 1994
GB/T15038-94
Note: 1) The specific sampling volume should be increased or decreased according to the requirements of the alcohol meter. 5.1.17 Analysis steps
Pour the sample prepared according to 5.1.16 into a clean, dry 500mL measuring cylinder, let it stand for a few minutes, wait for the bubbles to disappear, put in a clean, dry alcohol meter, press it gently, and do not let it touch the wall of the measuring cylinder. At the same time, insert a thermometer, balance for 5 minutes, observe horizontally, read the scale indication at the point tangent to the meniscus, and record the temperature at the same time. According to the measured alcohol meter indication and temperature, check Appendix B (Supplement) and convert it to alcohol content at 20℃. The result is expressed to one decimal place. 5.1.18 Allowable difference of results
The absolute value difference of the results of parallel tests shall not exceed 0.1% (V/V). 5.2 Total sugar and reducing sugar
Method 1 High performance liquid chromatography
5.2.1 Principle
The different distribution coefficients of various components in the sample between the liquid and solid phases are used to separate the fructose, glucose, sucrose and other components in the sample by passing the sample through a liquid chromatography column. Then, the sample is identified using a differential refractometer and quantified using an external standard method.
5.2.2 Methods—
5.2.2.1 Reagents and solutions
5.2.2.1.1 Ultrapure water (or freshly redistilled water degassed and filtered through a 0.45um water microfiltration membrane). 5.2.2.1.2 Sugar standard solution (containing 6.000 g/L2 of total sugar): Weigh 0.100 g (accurate to 0.0019) of dry glucose, fructose and sucrose respectively, transfer them into a 50 mL volumetric flask, and dilute to the mark with ultrapure water. The solution contains 2.000 g/L of glucose, fructose and sucrose respectively.
5.2.2.2 Instruments and equipment
High performance liquid chromatograph (equipped with a recording system or data processing device). 5.2.2.2.1
5.2.2.2.2
Differential refractometer.
Chromatographic column: 300 mm × 6.5 (inner diameter) mm, Sugar-PAK1 column. 5.2.2 .2.31
Microfiltration membrane: 0.45μm, water system.
5.2.2.2.4
Degassing device (or ultrasonic device).
5.2.2.2.5
5.2.2.3 Preparation of sample
Dilute the sample with ultrapure water (or fresh redistilled water degassed and filtered by 0.45um water system microfiltration membrane) to a sugar content of about 5g/L, and filter it with 0.45um water system microfiltration membrane. 5.2.2.4 Analysis steps
5.2.2.5 Chromatographic conditions
a. Column temperature: 90℃;
b. Mobile phase: ultrapure water;
c. Flow rate: 0.5mL/min
d. Injection volume: 50μL.
5.2.2.6 Measurement
Under the same chromatographic conditions, inject the sugar standard solution and the treated sample into the chromatograph respectively. After turning on the recording system, turn on the injection valve.
5.2.3 Method 2
5.2.3.1 Reagents and solutions
5.2.3.1.1 Acetonitrile: chromatographic grade (GR). 5.2.3.1.2 Ultrapure water; Same as 5.2.2.1.1. 5.2.3.1.3 Acetonitrile water (75+25): Mix acetonitrile and water in the ratio of (75+1025) (or adjust the ratio to the best separation effect according to the instrument), degas with a degasser, and then filter with a 0.45um oil filter membrane. This solution is used as the mobile phase.
5.2.3.1.4 Sugar standard solution (containing 45.000g/L of total sugar): Weigh 1.500g (accurate to 0.0019) of dry glucose, fructose, and sucrose respectively, transfer them into a 100mL volumetric flask, and dilute to the mark with ultrapure water. The solution contains 15.000 g/L of glucose, fructose and sucrose respectively.
5.2.3.2 Apparatus and equipment
High performance liquid chromatograph: same as 5.2.2.2.1. 5.2.3.2.1
5.2.3.2.2
Differential refractometer: same as 5.2.2.2. Chromatographic column: 150 mm x 5.0 (inner diameter) mm, Shim-pack CLCNH, column. 5.2.3.2.3
Microfiltration membrane: 0.45 μm, oil system.
5.2.3.2.4
Degassing device (or ultrasonic device).
5.2.3.2.5
5.2.3.3 Preparation of Samples
Dilute the sample with ultrapure water until the total sugar content is about 45g/L, and filter it with a 0.45um oil-based microfiltration membrane. 5.2.3.4 Analysis Steps
5.2.3.4.1 Chromatographic Conditions
a. Column temperature: room temperature:
b. Mobile phase: acetonitrile + water:
c. Flow rate: 2mL/min;
d. Injection volume: 20μL.
5.2.3.4.2 Measurement: Same as 5.2.2.6.
5.2.4 Calculation
X,=X,+1.05Z
Wherein, G, P, and Z can be directly calculated by substituting the values calculated by the instrument data processing device into formula (3) and (4) for calculation. Instruments without data processing devices can be calculated according to formula (5): X=
Reducing sugar content in sample (in terms of glucose), g/L; Wherein: X
Total sugar content in sample (in terms of glucose), g/L; -fruit essence content in sample, g/L; wwW.bzxz.Net
-Glucose content in sample, g/L; Z-
-Sucrose content in sample, g/L;
Coefficient for converting sucrose to glucose.
Content of component i (i=G, P, z) in the sample, g/L; peak area of component i in the sample spectrum;
Peak area of component i in the sugar standard sample spectrum; content of component i in the sugar standard solution, g/L; dilution factor of the sample.
The result is expressed to one decimal place.
5.2.5 Allowable difference of results
The difference in absolute values of the results of parallel tests shall not exceed 0.5g/L for dry and semi-dry wines, and 2g/L for sweet and semi-sweet wines.
Approved by the State Administration of Technical Supervision on May 5, 19947
Implemented on December 1, 1994
GB/T15038-94
5.2.6 Principle
Method 2 Direct titration
Use Fehling's solution and reducing sugar to azeotrope to form cuprous oxide precipitation. Use methylene blue as the indicator liquid to titrate the boiled Fehling's solution with the sample or the hydrolyzed sample. When the end point is reached, a slightly excessive amount of reducing sugar will reduce the blue methylene blue to colorless, indicating the end point. The total sugar or reducing sugar content is obtained based on the sample consumption. 5.2.7 Reagents and solutions
5.2.7.1 Hydrochloric acid solution (1+1).
5.2.7.2 Sodium hydroxide solution 200g/L.
5.2.7.3 Standard glucose solution 2.5g/L: Accurately weigh 2.50000g (weighed to 0.0001g), dry in an oven at 105-110℃
3h and cool in a desiccator, dissolve in water to 1000mL. 5.2.7.4 Methylene blue indicator solution 10g/L: Weigh 1.0g methylene blue, dissolve in water, and dilute to 100mL. 5.2.7.5 Fehling's A and B solutions
a. Preparation: Prepare according to 4.3.22 of GB603. b. Preliminary test for calibration: Take 5.00mL each of Fehling's A and B solutions in a 250mL conical flask, add 50mL of water, shake well, heat to boiling on an electric stove, and titrate with the prepared glucose standard solution in a boiling state. When the blue color of the solution disappears and turns red, add 2 drops of methylene blue indicator solution, continue to drip until the blue disappears, and record the volume of glucose standard solution consumed.
Formal test: Take 5.00mL each of Fehling's A and B solutions in a 250mL conical flask, add 50mL of water and 1mL less glucose standard solution than the preliminary test, heat to boiling, and keep for 2min, add 2 drops of methylene blue indicator solution, drip with glucose standard solution to the end point within 1min in a boiling state, and record the total volume of glucose standard solution consumed. c. Calculation
Where: F—5mL each of Fehling's A and B solutions is equivalent to the number of grams of glucose, g; m is the mass of glucose weighed, g;
V is the total volume of glucose standard solution consumed, mL. 5.2.8 Preparation of samples
5.2.8.1 Sample for total sugar measurement: Accurately pipette a certain amount of sample (V) into a 100mL volumetric flask 1) so that the total sugar content is 0.2~0.4g, add 5mL (1+1) hydrochloric acid solution. Add water to 20mL and shake well. Hydrolyze in a 68±1℃ water bath for 15min, take out and cool. Neutralize with 200g/L sodium hydroxide solution to neutrality, adjust the temperature to 20℃, and add water to the scale (Vz).
Note: 1) The volume of the volumetric flask can be determined according to the amount of sampling. 5.2.8.2 Sample for reducing sugar measurement: Accurately pipette a certain amount of sample (V,) into a 100mL volumetric flask so that the reducing sugar content is 0.2~0.4g, and add water to the scale. 5.2.9 Analysis steps
Substitute the sample for the glucose standard solution and perform the same operation as in 5.2.7.5b. Record the volume of the sample consumed (V3) and calculate the result according to formula (7).
When measuring dry wine samples according to 5.2.7.5b., the formal titration needs to be titrated to the endpoint with the glucose standard solution. The result is calculated according to formula (8).
5.2.10 Calculation
Approved by the State Administration of Technical Supervision on May 5, 1994F
(V./V.)xV
Implemented on December 1, 1994
GB/T15038-94
Content of total sugar or reducing sugar, g/L;
Where: Xo
x1000:
5mL of Fehling's A and B solution is equivalent to the number of grams of glucose, g; F
Volume of sample absorbed, mL;
V2Volume of sample after dilution or hydrolysis, mL; V3
-Volume of sample consumed, mL;
Accurate concentration of glucose standard solution, g/mL; Volume of glucose standard solution consumed, mL. The result should be expressed to one decimal place.
The allowable difference of the result
The error of two titrations in parallel tests shall not exceed 0.05mL. The third method, indirect iodine titration
5.2.12 Principle
(8)
The sample to be tested is azeotroped with excess Fehling's A and B solutions, and the reducing sugar contained therein reduces the divalent copper ions to cuprous oxide. The remaining divalent copper ions react with iodide ions under acidic conditions to generate a quantitative amount of iodine. The generated iodine is titrated with sodium thiosulfate standard solution to calculate the total sugar or reducing sugar content in the sample. The reaction formula is as follows: Cu2++CH,OH(CHOH),CHO-→CH,OH(CHOH)4COOH+Cu2O+（red）2Cu2++4-→2Cul+（white）+lz
Iz+2S203→2I+S02
5.2.13 Reagents and solutions
Sulfuric acid solution (1+5).
Potassium iodide solution 200g/L.
Hydrochloric acid solution (1+1).
Sodium hydroxide solution 200g/L.
Fehling's A and B solutions: Same as 5.2.7.5.
Sodium thiosulfate standard solution c (NazS,O,) = 0.1mol/L: Prepare and calibrate according to 4.6 of GB601. 5.2.13.6
Starch indicator solution 10g/L: Prepare according to 4.5.20 of GB603. 5.2.14 Preparation of test sample
Same as 5.2.8.
5.2.15 Analysis steps
In a 250mL standard ground-mouth conical flask, accurately add 5.00mL of Fehling's A and B solutions, 50.00mL of water, and 10.00mL of sample (5.2.14), shake well, put two glass beads, install a standard ground-mouth reflux condenser, and heat the solution to boiling within 2 minutes on an 800W heater. Start timing from the moment the solution completely starts to boil, keep boiling for 2 minutes, immediately remove it, and cool it in a cold water bath. After the solution is completely cooled, add 5mL of potassium iodide solution and 5mL of sulfuric acid solution while shaking, and immediately titrate with sodium thiosulfate standard solution. When it is close to the end point (the solution is light yellow), add 1mL of starch indicator solution and continue to titrate until it turns milky white, which is the end point. Record the volume of sodium thiosulfate standard solution consumed (V,). Perform a blank test with water instead of the sample to obtain (V.). 5.2.16 Calculation
X4 =c×(V．-V)x63.55× f
(V, /V.)xV
Approved by the State Administration of Technical Supervision on May 5, 1994
Implementation on December 1, 1994
GB/T15038-94
Wherein: X
Content of total sugar or reducing sugar (in terms of glucose), g/L; Molar concentration of sodium thiosulfate standard solution, mol/L; Vo
-Consumption of sodium thiosulfate standard solution in blank test volume, mL; volume of sodium thiosulfate standard solution consumed during sample titration, mL: V2—volume of sample absorbed, mL;
-volume of sample diluted or hydrolyzed to volume, mL; volume of sample absorbed during measurement, mL; redox ratio between copper and sugar (obtained by looking up Table 1 and Table 2 with c×(V);
molar mass of copper, g.
For total sugar, use the table
cX(Vo-Vi) X63.55
CX(Vo-V) X63.55
1)×63.55, the closest number to the value,
44.0053.00
For reducing sugar, use the table
37.0046.5055.00
The result should be expressed to one decimal place.
5.2.17 Allowable difference of results
Same as 5.2.11.
5.3 Titration of acid
Method 1 Potentiometric titration
5.3.1 Principle
Use pH glass electrode as indicator electrode, saturated calomel electrode as reference electrode, use acidometer or potentiometric titrator to indicate pH of solution, titrate the test solution with sodium hydroxide standard solution to pH 9.0 as end point, calculate titration acid of the sample according to the amount of sodium hydroxide solution, and the result is expressed as the main acid of the sample. The reaction formula is: RCOOH+NaOH-
5.3.2 Reagents and solutions
-RCOONa+H,O
5.3.2.1 Sodium hydroxide standard solution c (NaOH) = 0.05mol/L: Prepare and calibrate according to Article 4.1 of GB601, and dilute accurately.
5.3.2.2 Phenol indicator solution 10g/L: Prepare according to 4.5.22 of GB603. 5.3.3 Instruments
5.3.3.1 Potentiometric titrator.
5.3.3.2 pH meter (acidity meter): accuracy 0.002pH, with electromagnetic stirrer. 5.3.4 Analysis steps
5.3.4.1 Calibration of instrument: Install the instrument according to the instruction manual, turn on the power, insert the glass (indicator) electrode and calomel (reference) electrode into the borax standard buffer solution (pH=9.18325℃), and calibrate and position according to the liquid temperature. 5.3.42 Sample determination
Put 10.00mL of sample in a 100mL beaker, add 50mL of water, insert the electrode, put in a rotor, place it on the electromagnetic stirrer, start stirring, and titrate with sodium hydroxide standard solution. The titration speed can be slightly faster at the beginning. When the pH of the sample solution reaches 8.0, slow down the titration speed and add half a drop of solution each time until the pH reaches 9.0, which is the end point. Record the volume of the sodium hydroxide standard solution consumed. Perform a blank test at the same time. Sparkling wine and aerated sparkling wine need to remove carbon dioxide before testing. 5.3.5 Calculation
Approved by the State Administration of Technical Supervision on May 5, 1994, implemented on December 1, 1994
GB/T15038-94
X, = cx(/-Vo)×s,
Wherein: Xs—the content of titrating acid in the sample (calculated as tartaric acid), g/L; c—the molar concentration of sodium hydroxide standard solution, mol/L; Vo—the volume of sodium hydroxide standard solution consumed in the blank test, mL; V—the volume of the sodium hydroxide standard solution consumed during sample titration, mL; Vz—the volume of the sample absorbed, mL;
..(10)
—the mass of the main acid in the sample expressed in grams equivalent to 1.00mL of sodium hydroxide standard solution [c(NaOH)=1.000mol/L]. S calcic acid = 0.075; S tsaoko stock = 0.067; S citric acid = 0.064; S tsaoko = 0.045. The results should be expressed to one decimal place.
5.3.6 Permissible difference of results
The absolute value difference of the results of parallel tests shall not exceed 0.1g/L. Method 2 Indicator method
5.3.7 Principle
Using the principle of acid-base titration, phenol is used as an indicator and titrated with a standard alkali solution. The titrated acid content is calculated based on the amount of alkali used and expressed as the main acid contained in the sample. 5.3.8 Reagents and solutions
Same as 5.3.2.
5.3.9 Analysis steps
Take 2-5 mL of sample adjusted to 20℃ (the sampling volume can be increased or decreased according to the color depth of the wine), place it in a 250 mL conical flask, add 50 mL of neutral distilled water, and add 2 drops of phenolic indicator solution. After shaking, immediately titrate to the endpoint with sodium hydroxide standard solution, and keep it without changing color within 30 seconds. Record the volume (V) of sodium hydroxide standard solution consumed. Perform a blank test at the same time. Sparkling wine and aerated sparkling wine need to remove carbon dioxide before determination. 5.3.10 Calculation
Same as 5.3.5.
5.3.11 Permissible difference of results
Same as 5.3.6.
5.4 Volatile acid
5.4.1 Principle
The low boiling point acids in the sample, namely volatile acids, are distilled out by distillation, and then titrated with a standard alkali solution. After calculation and correction, the content of volatile acids in the sample is obtained. 5.4.2 Reagents and solutions
5.4.2.1 Tartaric acid solution 20%.
Others are the same as in 5.3.8.
5.4.3 Apparatus and equipment
Any distillation device that meets the following three requirements can be used for this test. The volatile acid distillation device recommended in Appendix D (reference) can also be used.
a. Take 20mL of distilled water as the sample for distillation, and the distilled water should not contain carbon dioxide. b. Take 20mL of 0.1mol/L acetic acid as the sample for distillation, and the recovery rate should be greater than or equal to 99.5%. c. Take 20mL 0.1mol/L lactic acid as the sample for distillation, and the recovery rate should be less than or equal to 0.5%. 5.4.4 Analysis steps
Install the volatile acid distillation device according to the instrument requirements. Take an appropriate amount of 20℃ sample (V) and tartaric acid solution and distill on the device. Collect 100mL of distillate. Heat the distillate to boiling, add 2 drops of phenol anhydride indicator solution, and titrate with sodium hydroxide standard solution until pink. The end point is that there is no color change within 30 seconds. Record the volume of sodium hydroxide standard solution consumed (V).
5.4.5 Calculation
c×V×60.0
Wherein: X is the content of volatile acid in the sample (in terms of acetic acid), g/L; - the molar concentration of the sodium hydroxide standard solution, mol/L; V
the volume of the sodium hydroxide standard solution consumed, mL; (11)
and 1.00mL sodium hydroxide standard solution [[c(Na0H)=1.000mol/L]] equivalent to the mass of acetic acid in grams, g;
-sampling volume, mL.
If the volatile acid content is close to or exceeds the physical and chemical index, correction is required. When correcting, convert according to formula (12): H=X,-UX1.875+JX0.9375):
Where: H
-real volatile acid content (in acetic acid) in the sample, g/L; measured volatile acid content, g/L;
free sulfur dioxide content, g/L;
-bound sulfur dioxide content, g/L;
-free sulfur dioxide conversion coefficient to acetic acid; 1.875
bound sulfur dioxide conversion coefficient to acetic acid. The result should be expressed to one decimal place.
5.46 Allowable error of results
The absolute value difference of the results of parallel tests shall not exceed 5% of the average value. 5.5 Free sulfur dioxide
Method 1 Oxidation method
5.5.1 Principle
(12)
Under low temperature conditions, the free sulfur dioxide in the sample reacts with excess hydrogen peroxide to generate sulfuric acid, which is then titrated with an alkali standard solution. The free sulfur dioxide content in the sample can be obtained in this way. 5.5.2 Reagents and solutions
5.5.2.1 Hydrogen peroxide solution 0.3%: Take 1 mL of 30% hydrogen peroxide (stored in the refrigerator after opening) and dilute it to 100 mL with water. Prepare it fresh every day.
5.5.2.2 Phosphoric acid solution 25%: Measure 295 mL of 85% phosphoric acid and dilute it to 1000 mL with water. 5.5.2.3 Sodium hydroxide standard solution c (NaOH) = 0.01 mol/L: Accurately pipette 100 mL of sodium hydroxide standard solution (5.3.2.1) and dilute to 500 mL with carbon dioxide-free distilled water. Store in a bottle with a soda lime tube on a rubber stopper and reconstitute weekly.
5.5.2.4 Methyl red and methyl blue mixed indicator solution: Prepare according to 4.5.7 of GB603. 5.5.3 Instruments
5.5.3.1 Sulfur dioxide determination device See Figure 4. Approved by the State Administration of Technical Supervision on May 5, 1994 and implemented on December 1, 1994
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.